A new method to assess the causes of the changes in the extreme precipitation under changed climate was proposed. Previous methods have not explicitly considered the contribution of changes in the near surface atmospheric humidity to the changes in the extreme precipitation under changed climate, although the changes in the extreme precipitation can be affected by the changes in near surface atmospheric humidity through the changes in lifting condensation level. The new method can consider changes in near surface atmospheric humidity as well as the changes in atmospheric circulation and lapse rate of the ascending air parcel. The new method was applied to atmosphere-ocean coupled model output, provided for the Coupled Model Intercomparison Project Phase 5. It was confirmed that the new method can assess the regional difference of the contribution of the changes in near surface atmospheric humidity to the changes in the extreme precipitation with climate change.
